16 Jun Ch 24_Cancer Cells – Cigarette smoking is a major risk factor in the development
Question 1 (15 points)
Cigarette smoking is a major risk factor in the development of non-small cell lung cancer (NSCLC), which accounts for 80% of all lung cancers. NSCLC is characterized by poor prognosis and resistance to chemotherapy. To understand if nicotine affects this resistance, lung cancer cell lines were treated with chemotherapeutic drugs gemcitabine, Cisplatin and Taxol, in presence and absence of nicotine.
A. Three different NSCLC cell lines, A549, NCI-H23 and H1299, were examined by TUNEL assay which detect cells that are undergoing apoptosis. Various treatments are shown on the figure showing the results. What are your conclusions for the following results?
B. A549 cells were incubated with the drug as mentioned above and an additional chemotherapeutic agent camptothecin was also used in presence and absence of nicotine. The cells were lysed and extracts were run on SDS-PAGE gels, blotted and probed with antibodies against the indicated proteins. PARP is a protein cleaved during apoptosis. What can you deduce from the data shown below? What is the purpose of assessing levels of p53, p21 and actin?
The data that can be deduced is that
C. Survivin and XIAP are both members of IAP (inhibitors of apoptotic proteins) family. A549 cells were treated in presence and absence of nicotine and presence and absence of LY294002, an inhibitor of PI-3kinase. The levels of PARP, XIAP, surviving and actin were assessed as shown in the western blot below. The graph shows the results of TUNEL assay in which A549 cells were transfected with the indicated SiRNAs. “None” is the control where no RNS was transfected. Control Si-RNA1 and 2 are non-specific Si-RNAs. What do these studies suggest about the mechanism of nicotine action?
Question 2 (15 points)
Part A: In the hypothetical pathway below, ligand A binds to Receptor B and causes phosphorylation of Protein C. Phosphorylated protein C can travel to the nucleus and elicit transcription of genes resulting in cell cyle progression and proliferation. Protein D can inhibit the phosphorylation of protein C. Identify ONE pathway component that can act as an oncogene and ONE pathway component that can act as tumor suppressors. Explain why.
Part B: In the hypothetical pathway below, ligand A binds to Receptor B and causes phosphorylation of Protein C. Phosphorylated protein C can travel to the nucleus and elicit transcription of genes resulting in apoptosis and cell cycle arrest. Protein D can inhibit the phosphorylation of protein C. Identify ONE pathway component that can act as an oncogene and ONE pathway components that can act as tumor suppressors. Explain why.
d. Can you provide a biological explanation for why the prognosis is poorer for patients who smoke during chemotherapy compared to those who quit smoking prior to it?
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(Assuming everyone is supposed to put in 100% effort.
(Rate it on a scale of 1-10)
Something you appreciate about this person’s effort/contribution
Something you expect from this person’s contribution for next time
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